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Full text of "The Morphology And Evolution Of The Apes And Man"

THE SKELETON AND TEETH              115
by a strong, thick, post-glenoid process. An endoglenoid tubercle is present, and there is sometimes a small styloid process; so we have here two points in which the skull differs from that of the Gibbon. As in the Gibbon, there are neither vaginal nor mastoid processes.
The carotid canal tunnels the petrous temporal in a direction which is first upwards and then forwards; so the foramen is obtrusive on the basis cranii. In the Gibbon, on the other hand, the canal runs straight forwards, so the foramen is not so plain.
The anterior condyloid foramen is sometimes replaced by two apertures, but it is always single in the Gibbons. The foramen magnum is placed far back as in the Gibbons, and it lies partly on the basis cranii and partly on the occipital plane.
The occipital condyles are small. Their mesial borders do not diverge so much as in the Gibbons.
It is not usual to meet with anomalies round the foramen magnum, but the upper part of the suspensory ligament may be ossified, when a spicule of bone will be seen on the anterior border of the foramen
magnum.
The Cranial Cavity.—The anterior compartment of the cranial cavity is reduced by the globular roofs of the orbits. The cribriform plate of the ethmoid articulates with the pre-sphenoid as in Man, but the crista galli is rudimentary or absent.
The anterior and posterior clinoid processes are frequently connected, and the tentorium, which is attached to them anteriorly, is said by Owen (,276) to stop posteriorly at the petrosals. The Gasserian ganglion may be concealed by a shelf of bone continuous with the